MULTI-STAGE ROD PUMP UNIT Russian patent published in 2012 - IPC F04B47/02 

FIELD: engines and pumps.

SUBSTANCE: unit includes operating cylinder with side holes, differential plunger with plungers of small and large diameter, and suction and delivery valves. Operating cylinder is fixed and sealed inside the casing by means of anchor shoe and lock. Casing is equipped with suction valve and filter in lower part and its upper part is attached through anchor shoe to tubing string. Differential plunger is equipped with internal fluid flow channel and consists of more than one plunger of small diameter and more than one plunger of large diameter. Plungers of small diameter are equipped with side holes located in upper part and contact the seals located inside operating cylinder under side holes. Plungers of large diameter are equipped with delivery valves. Operating cylinder is fixed on rod string. Ratio of small and large diameters of plungers is 0.48 to 0.84; ratio of plunger lengths is (0.8-1) to (1-0.8).

EFFECT: improving efficiency of the unit and simplifying the erection and removal.

1 dwg